Chapter 3 Flashcards Preview

SON111AB-Physics > Chapter 3 > Flashcards

Flashcards in Chapter 3 Deck (51)
Loading flashcards...
1
Q

Aperture

A

size of a transducer element (for a single-element transducer) or group of elements (for an array)

2
Q

Apodization

A

nonuniform (i.e involving different voltage amplitudes) driving of elements to an array to reduce grating lobes

3
Q

Array

A

a transducer assembly containing several piezoelectric elements

4
Q

Axial

A

in the direction of the transducer axis (sound travel direction)

5
Q

Axial Resolution

A

the minimum reflector separation along the sound path that is required to produce separate echoes (i.e to distinguish between two reflectors)

6
Q

Beam

A

region containing continuous wave sound; region through which a sound pulse propagates

7
Q

Composite

A

combination of piezoelectric ceramic and a nonpiezoelectric polymer

8
Q

Convex array

A

curved linear array

9
Q

Crystal

A

element

10
Q

Curie Point

A

temperature at which an element material loses its piezoelectric properties

11
Q

Damping

A

material attached to the rear face of transducer element to reduce pulse duration; the process of pulse duration reduction

12
Q

Detail resolution

A

the ability to image fine detail and to distinguish closely spaced reflectors.

13
Q

Disk

A

a thin, flat, circular object

14
Q

Dynamic aperture

A

aperture that increases with increasing focal length (to maintain constant focal width)

15
Q

Dynamic focusing

A

continuously variable reception focusing that follows the increasing depth of the transmitted pulse as it travels

16
Q

Element

A

the piezoelectric component of transducer assembly

17
Q

Elevational resolution

A

the detail resolution in the direction perpendicular to the scan plane. it its equal to the section thickness and is the source of section thickness artifact

18
Q

far zone

A

the region of a sound beam in which the beam diameter increases as the distance from the transducer increases; also called far field

19
Q

focal length

A

distance from a focused transducer to the center of a focal region or to the location of the spatial peak intensity.

20
Q

focal region

A

region of minimum beam diameter and area

21
Q

focal zone

A

length of the focal region

22
Q

focus

A

the concentration of the sound beam into a smaller beam area that would exist otherwise

23
Q

grating lobes

A

additional weaker beams of sound traveling out in directions different from the primary beam as a result of the multi-element structure of transducer arrays

24
Q

lateral

A

perpendicular to the direction of sound travel

25
Q

lateral resolution

A

minimum reflector separation perpendicular to the sound path that is required to produce separate echoes

26
Q

lead zirconate titanate

A

a ceramic piezoelectric material. abb PZT.

27
Q

lens

A

a curved material that focuses a sound or light beam

28
Q

linear

A

adjectival form of line

29
Q

linear array

A

array made of rectangular elements arranged in straight line

30
Q

linear phased array

A

linear array operated by applying voltage pulses to all elements, but with small time differences (phasing) to direct ultrasound pulses out in various directions

31
Q

linear sequenced array

A

linear array operated by applying voltage pulses to groups of elements sequentially.

32
Q

matching layer

A

material attached to the front face of a transducer element to reduce the reflections at the transducer surface

33
Q

natural focus

A

the narrowing of a sound beam that occurs with an unfocused flat transducer element

34
Q

near zone

A

the region of sound beam in which the beam diameter decreases as the distance form the transducer increases; also called near field

35
Q

operating frequency

A

preferred (max efficiency) frequency of operation of a transducer

36
Q

phased array

A

an array that steers and focuses the beam electronically (with short time delays)

37
Q

phased linear array

A

linear sequenced array with phased focusing added linear sequenced array with phased steering of pulses to produce a parallelogram- shaped display

38
Q

piezoelectricity

A

conversion of pressure to electric voltage

39
Q

probe

A

transducer assembly

40
Q

resolution

A

the ability to distinguish echoes in terms of space, time, or strength (called detail, temporal, and contrast resolutions)

41
Q

resonance frequency

A

operating frequency

42
Q

scanhead

A

transducer assembly

43
Q

sector

A

a geometric figure bounded by two radii and the arc of the circle included between them

44
Q

sensitivity

A

ability of an imaging system to detect weak echoes

45
Q

side lobes

A

weaker beams of sound traveling out from a single element in direction different form those of a primary beam

46
Q

sound beam

A

the region of a medium that contains virtually all of the sound produced by a transducer

47
Q

source

A

an emitter of ultrasound; transducer

48
Q

transducer

A

a device that converts energy from one form to another

49
Q

transducer assembly

A

transducer element with damping and matching material assembled in a case

50
Q

ultrasound transducer

A

a device that converts electric energy to ultrasound energy; and vice versa

51
Q

vector array

A

linear sequenced array that emits pulses from different starting points and (by phasing) in different directions.